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Re: baseline performance test using java ...

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From	lewbloch <lewbloch@gmail.com>
Newsgroups	comp.lang.java.programmer
Subject	Re: baseline performance test using java ...
Date	Mon, 4 Jul 2011 03:53:33 -0700 (PDT)
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Abu Yahya wrote:
> Patricia Shanahan wrote:
>> Abu Yahya wrote:
>>> If you need to build them, you'd need a StringBuilder. And if you need
>>> support for multiple threads AND need to modify them, you'd need a
>>> StringBuffer.
>

>> Often, the StringBuffer locking is not strong enough to be really
>> useful. If, for example, a thread needs to append two strings to the
>> buffer and have them appear consecutively in the resulting string, it
>> needs synchronization at a higher level.
>

> True. StringBuffer's locking will only help in guaranteeing an output in
> which either the first string /or/ the second string is /completely/
> appended first. If the order matters, the built-in locking won't help.

That's a small part of the story, and not accurate anyway.

 StringBuffer sb;
 ...
 sb.append( firstString ).append( secondString );

/happens-before/ guarantees that the second 'append()' will
concatenate after the first one.  Once the second 'append()'
completes, all threads are guaranteed to see the effects of both
'append()'s.  The synchronization inbuilt to 'StringBuffer' does not
guarantee that some thread won't intervene between the two
'append()'s.

--
Lew

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Thread

baseline performance test using java ... lbrt chx _ gemale kom - 2011-07-03 17:53 +0000
  Re: baseline performance test using java ... Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-07-03 14:08 -0400
  Re: baseline performance test using java ... Abu Yahya <abu_yahya@invalid.com> - 2011-07-04 00:03 +0530
    Re: baseline performance test using java ... Patricia Shanahan <pats@acm.org> - 2011-07-03 11:45 -0700
      Re: baseline performance test using java ... Abu Yahya <abu_yahya@invalid.com> - 2011-07-04 06:52 +0530
        Re: baseline performance test using java ... lewbloch <lewbloch@gmail.com> - 2011-07-04 03:53 -0700
    Re: baseline performance test using java ... lewbloch <lewbloch@gmail.com> - 2011-07-04 03:44 -0700
  Re: baseline performance test using java ... Patricia Shanahan <pats@acm.org> - 2011-07-03 12:09 -0700
  Re: baseline performance test using java ... Patricia Shanahan <pats@acm.org> - 2011-07-04 09:54 -0700

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